Solid State Lighting Devices with Reduced Melatonin Suppression
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Solution Overview
Problem
Conventional solid state lighting devices often disrupt circadian rhythms due to high blue light emission, leading to melatonin suppression and poor color rendering index (CRI) values, particularly in outdoor applications, which results in light pollution and adverse health effects.
Innovation Solution
A solid state lighting device comprising at least one electrically activated solid state emitter with lumiphoric materials that generate emissions within specific wavelength ranges (430-480 nm, 540-570 nm, and 605-650 nm) to produce aggregated emissions with a correlated color temperature (CCT) between 1800 K to 2300 K and a Duv value of at least 0.005, maintaining high CRI values while reducing circadian stimulus and light pollution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional solid state lighting devices use blue LED emissions with yellow phosphor to generate white light, then luminous efficacy is improved, but melatonin suppression increases and circadian rhythms are disrupted
Solution Approach 1:
The patent changes the spectral parameters of the light source by using violet LED emissions (405-420 nm) instead of blue emissions, and by selecting phosphors with specific peak wavelengths (480-500 nm, 560-580 nm, 620-750 nm). This parameter change shifts the spectrum away from the melanopic sensitivity peak at 480 nm, reducing melatonin suppression while maintaining luminous efficacy through optimized phosphor selection and combination.
Solution Approach 2:
The patent employs composite phosphor materials with multiple peak wavelengths to create a broad spectrum that excludes the harmful 480 nm blue region. By combining phosphors emitting in the cyan (480-500 nm), yellow-green (560-580 nm), and red (620-750 nm) regions, the invention creates a composite light source that maintains high luminous efficacy while eliminating melatonin suppression.
2Use of energy by moving object
If blue LED emissions are used to stimulate yellow phosphor for white light generation, then energy efficiency is enhanced, but color rendering index (CRI) values deteriorate
Solution Approach 1:
The patent uses a composite phosphor system with three distinct peak wavelength regions (cyan 480-500 nm, yellow-green 560-580 nm, and red 620-750 nm) to generate a broad spectrum that covers all visible wavelengths. This composite approach enables high CRI values by providing complete spectral coverage while maintaining energy efficiency through the use of violet LED excitation and optimized phosphor combinations.
Solution Approach 2:
The patent changes the spectral distribution parameters by eliminating the 480 nm blue peak and instead creating peaks at 480-500 nm, 560-580 nm, and 620-750 nm. This parameter transformation broadens the spectrum to include all visible wavelengths, improving color rendering while maintaining the energy efficiency benefits of solid state lighting.
3Illumination intensity
If blue light emissions are increased to improve luminous output, then illuminance is improved, but light pollution and circadian rhythm disruption worsen
Solution Approach 1:
The patent changes the spectral parameters by using violet LED emissions (405-420 nm) to excite phosphors that emit in the cyan (480-500 nm), yellow-green (560-580 nm), and red (620-750 nm) regions. This parameter change produces high luminous output through efficient phosphor conversion while eliminating the harmful 480 nm blue light that causes light pollution and circadian rhythm disruption.
Solution Approach 2:
The patent converts the potentially harmful violet LED emissions (405-420 nm) into beneficial broad-spectrum visible light through phosphor downconversion. The violet light serves as an efficient excitation source that, when converted by the phosphor composite, produces high-quality visible illumination without the harmful blue component, thus converting a potentially harmful wavelength into a beneficial light source.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces melatonin suppression, enhances energy efficiency, and provides superior color rendering while minimizing light pollution, achieving a balance between circadian rhythm preservation and luminous efficacy.
Implementation Method 1
LEDs are solid state devices that convert electrical energy to light and generally include one or more active layers of semiconductor material
Implementation Method 2
Solid state emitters may include lumiphoric materials (also known as lumiphors) that absorb a portion of emissions having a first peak wavelength emitted by the emitter and re-emit light having a second peak wavelength that differs from the first peak wavelength
Data Source
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Figure 5A~5B
AI summary
Solid state lighting devices with melatonin suppression characteristics that ameliorate or reduce symptoms of circadian rhythm disorders or other health conditions. Aspects disclosed herein additionally relate to providing one or more of the foregoing effects while maintaining color rendering index (CRI) values acceptably high for the intended use, as well as providing lighting devices with high luminous efficacy and enhanced energy efficiency. A solid state lighting device includes one or more solid state emitters and one or more lumiphoric materials that provide aggregated emissions of the solid state lighting device. The aggregated emissions have a warm correlated color temperature (CCT) with a color point that is off of the blackbody locus (BBL) by a certain distance.